This invention is directed to novel multifunctional antiwear and antioxidant additives and lubricant compositions containing same.
Lubricants, such as lubricating oils and greases are subject to oxidative deterioration at elevated temperatures or upon prolonged exposure to the elements. Such deterioration is evidenced, in many instances, by an increase in acidity and in viscosity. It can cause metal parts to corrode. Additionally, severe oxidation leads to a loss of lubrication properties. Improved antioxidants are clearly needed.
Antioxidants or oxidation inhibitors are used to minimize the effects of oil deterioration that occur when hot oil is contacted with air. The degree and rate of oxidation will depend on temperature, air and oil flow rates and, of particular importance, on the presence of metals that may catalytically promote oxidation.
Water (moisture) is another critical problem which can bring about ideal conditions for corrosion and damage of metal surfaces of materials in contact therewith. In the lubrication of internal combustion engines, for example, quantities of water are often present as a separate phase within the lubricating system. Another serious problem in respect to metallic surfaces in contact with adjacent metallic surfaces is the surface wear caused by the contact of such surfaces. The need for improving lubricity and providing antioxidant and antiwear additives for lubricating oils to meet the ever changing requirements of modern engines is clearly well known. One material capable of simultaneously effectively coping with these serious problems is highly desirous.
It has now been found that the use of phosphorodithioate derived succinic anhydride amide/ester/amine salt derivatives provide exceptional antioxidant and antiwear activity with significant rust inhibiting, and potential corrosion inhibiting properties.
The use of phosphorodithioate compositions, especially the corresponding salts of phosphorodithioate, such as zinc dialkylphosphorodithioates (commonly known as zinc dithiophosphates) have found widespread commercial use for several decades in engine oils as multifunctional antiwear, peroxide decomposing, and bearing corrosion inhibiting additives.
The use of succinic anhydride derivatives has been extensively reported as having beneficial antirust properties as well as detergency/dispersancy characteristics.
The herein disclosed remarkable benefits of the compositions in accordance with the present invention, are also expected for a variety of synthetic and mineral oil based lubricants. The compositions of matter and the lubricant compositions are believed to be novel. To the best of our knowledge, these compositions have not been previously used as multifunctional additives in lubricating oils, greases or fuel applications.